ICs ranging from ASICs to full custom ICs include a transistor embedded silicon based structure, and an interconnect structure with metal layers for power routing purposes, namely, the provision of an IC power supply net, and transistor interconnection purposes. An IC power supply net includes a power net for connection to the power ports (hereinafter denoted “VDD ports”) of an IC's power consuming entities (hereinafter denoted “PCEs”), and a ground net for connection to their ground ports (hereinafter denoted “GND ports”). PCEs include full custom macrocells, and standard cell placement areas and, since an IC can have a hierarchically designed structure, a PCE in a non-leaf layer may include lower layer PCEs. IC power routing starts with the provision of an initial IC floorplan with PCEs, and involves determining an IC power supply net physical layout, calculating the widths of the wires making up its power and ground nets, determining slot spread in the wires to satisfy IC fabrication requirements, passing an IC power supply net verification procedure, and if necessary, modifying the IC floorplan and/or the IC power supply net.